CALCRUST NORTH: Tectonics of the California Coast Ranges in the San Francisco Bay Area

这项研究计划是对旧金山湾区现今的地壳构造和加州中部海岸山脉的演化进行调查，圣安德烈亚斯断层系统在那里通过一个连续分叉的复杂结构向东伸展，进入卡拉维拉斯、海沃德和格林维尔断层，这一过程在该地区的地震活动地图上很容易看到。关于板块边界运动的地壳调节的相互竞争的假设将得到检验。将寻找关于这一系统地壳动力学的令人信服的现代范例的证据，在该范例中，上地壳块体及其边界断层向东移动，在中地壳滑脱之上，形成东西向逆冲断层、构造楔形和褶皱带组成的区域复合体。这项拟议的研究是对从旧金山湾向东到大峡谷西部边界的地壳第三维度的综合调查。这项研究将结合现代地震学方法和地质/大地测量约束。反射地震剖面、自然事件P波和S波层析成像、正在进行的东湾断层地质研究以及关于湾区地壳变形的新数据将在加利福尼亚州中部板块边界的共同几何框架内联合解释。反射数据是本研究的关键，也是本项目的主要关注点。该地区160公里的高质量行业“规范”数据可供购买，并可进行再处理以进行更深层次的成像。1991年9月，在美国地质勘探局的支持下，在海湾、河流和近海水域拍摄的新的BASIX(湾区地震成像实验)海洋/陆地剖面提供了更有价值的区域覆盖范围，数据现已在伯克利获得。

This research program is an investigation of the present crustal tectonics and the evolution of the central California coast ranges in the San Francisco Bay region, where the San Andreas fault system splays eastward through a complex of successive bifurcations into the Calaveras, Hayward and Greenville faults, a process readily visible in the seismicity maps of the area. Competing hypotheses for crustal accommodation of the plate boundary motion will be tested. Evidence will be sought on the compelling modern paradigm for the crustal dynamics of this system, in which upper crustal blocks along with their bounding faults move eastward, above a mid-crustal decollement, creating the regional complex of east- and west-vergent thrust faults, tectonic wedges and fold belts. The proposed research is an integrated investigation of the crust's third dimension eastward from San Francisco Bay to the western boundary of the Great Valley. Modern seismological methods and geological/geodetic constraints will be combined in the study. Reflection seismic profiles, natural-event P- and S-wave tomography, ongoing geological studies of East Bay faults, and new data on crustal deformation in the Bay Area will be interpreted jointly within a common geometrical framework for the plate boundary in central California. Reflection data are key to this study, and a primary focus in this project. 160 km of high- quality industry "spec" data in the area are available for purchase and can be reprocessed for deeper imaging. The new BASIX (Bay Area Seismic Imaging eXperiment) marine/land profile, shot in the Bay, River and offshore waters with USGS support in September 1991, provides additional valuable coverage of the region, and the data are in hand at Berkeley.